Vertical Takeoff and Landing (VTOL) Air Vehicle

ABSTRACT

A flight control apparatus for fixed-wing aircraft includes a first port wing and first starboard wing, a first port swash plate coupled between a first port rotor and first port electric motor, the first port electric motor coupled to the first port wing, and a first starboard swash plate coupled between a first starboard rotor and first starboard electric motor, the first starboard electric motor coupled to the first starboard wing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US14/36863 filed May 5, 2014, which claims priority to and thebenefit of U.S. Provisional Application No. 61/819,487 filed May 3,2013, the disclosures of both of which are incorporated by referenceherein for all purposes.

FIELD OF THE INVENTION

The field of the invention relates to aircraft flight control, and moreparticularly to aircraft flight control of rotary fixed-wing aircraft.

DESCRIPTION OF THE RELATED ART

Many applications exist for remotely or autonomously-piloted unmannedaerial vehicles (UAVs) that are able to take off, loiter, and landwithout the benefit of a runway. Vertical takeoff and landing (VTOL)vehicles address this limitation and may come in the form ofhand-launched aerial vehicles having a main wing and avertical/horizontal tail control surfaces, or three or four-rotorcopters that are operable to take off and land vertically. Aerialvehicles having a main wing and vertical/horizontal tail controlsurfaces tend to be more efficient and faster in cruise, while rotorcopters are less efficient in forward flight but have takeoff andlanding advantageous.

A need continues to exist to design and manufacturer aerial vehiclesthat are efficient in flight and that can takeoff and land vertically.

SUMMARY

A flight control apparatus is disclosed for fixed-wing aircraft thatincludes a first port wing and a first starboard wing, a first portswash plate coupled between a first port rotor and a first port electricmotor, the first port electric motor coupled to the first port wing, anda first starboard swash plate coupled between a first starboard rotorand a first starboard electric motor, the first starboard electric motorcoupled to the first starboard wing. The apparatus may also include asecond port wing and second starboard wing, a second port swash platecoupled between a second port rotor and second port electric motor, thesecond port electric motor coupled to the second port wing, and a secondstarboard swash plate coupled between a second starboard rotor andsecond starboard electric motor, the second starboard electric motorcoupled to the second starboard wing. In one embodiment, the apparatusmay include a horizontal stabilizer coupled to a fuselage and anelevator rotatably coupled to the horizontal stabilizer, the fuselagecoupled between the first port wing and second starboard wing, and mayinclude a port aileron rotatably disposed on a trailing edge of thefirst port wing and a starboard aileron rotatably disposed on a trailingedge of the first starboard wing. The apparatus may include first andsecond landing gear attached to the first port wing and first starboardwing, respectively, and may include a third landing gear attached to thehorizontal stabilizer.

A method of flight control for fixed-wing aircraft is also disclosedthat includes inducing a right roll of a fuselage coupled between afirst port wing and a first starboard wing, in response to i) generatingin a first port rotor a positive rotational moment in response toactuation of a first port swash plate, the first port rotor rotatablycoupled to the first port wing, and ii) generating in a first starboardrotor a negative rotational moment in response to actuation of a firststarboard swash plate, the first starboard rotor rotatably coupled tothe first starboard wing. In some embodiments, the method may includegenerating asymmetric collective control between the first port rotorand the first starboard rotor to induce a yaw moment about the fuselage.When used together, the asymmetric collective control, positiverotational moment and negative rotational moment can enable acoordinated turn of the port and starboard wings. In one embodiment, themethod may also include inducing a left roll of a fuselage in responseto generating in the first port rotor a negative rotational moment inresponse to actuation of the first port swash plate and generating inthe starboard rotor a positive rotational moment in response toactuation of the first starboard swash plate. The method may alsoinclude providing pitch control of the fuselage in response toasymmetric collective control provided between at least the first portrotor and a second port rotor rotatably coupled to a second port wing,the second port wing coupled to the fuselage. In one embodiment, themethod may include providing pitch control of the fuselage in responseto providing differential angular velocities (RPM) between at least thefirst port rotor and a second port rotor rotatably coupled to a secondport wing, the second port wing coupled to the fuselage, and may includeproviding pitch control of the fuselage in response to providingdifferential angular velocities (RPM) between the first starboard rotorand a second starboard rotor rotatably coupled to a second starboardwing. Further embodiments may include providing elevator controlcomplementary to the providing pitch control to supplement the pitchingmoment with an additional pitching moment. In one embodiment, the methodmay include providing pitch control of the fuselage in response toactuating an elevator. Right roll of the fuselage may be induced inresponse to generating in a second port rotor a positive rotationalmoment in response to actuation of a second port swash plate, the secondport rotor rotatably coupled to a second port wing, and generating in asecond starboard rotor a negative rotational moment in response toactuation of a second starboard swash plate, the second starboard rotorrotatably coupled to a second starboard wing so that the positive andnegative moments of force generated in the second port rotor and secondstarboard rotor induce a right roll of the second port and secondstarboard wings. The method may also include supplementing the rightroll of the fuselage in response to actuating port and starboardailerons rotatably coupled to the second port wing and second starboardwing, respectively.

A further method of vertical take-off and horizontal flight of afixed-wing aircraft, is disclosed that generating thrust in a first portrotor driven by a first port electric motor on a first port wing and afirst starboard rotor driven by a first starboard motor on a firststarboard wing to induce vertical takeoff of a fuselage coupled betweenthe first port wing and a first starboard wing. In this disclosedmethod, the method may also include generating a negative rotationalmoment in the first port rotor and first starboard rotor using cyclicrotor blade control to accomplish transition of the first port and firststarboard wings from vertical takeoff to horizontal flight, and mayinclude generating thrust in a second port rotor driven by a second portelectric motor on a second port wing and a second starboard rotor drivenby a second starboard motor on a second starboard wing. The fuselage maybe transitioned from vertical takeoff to horizontal flight in a numberof disclosed embodiments, including i) in response to asymmetriccollective control as between the first port rotor and first starboardrotor on the one hand and the second port rotor and the second starboardrotor on the other hand, and ii) in response to differential rotorangular velocity control (RPM) control as between the first port rotorand first starboard rotor on the one hand and the second port rotor andthe second starboard rotor on the other. Horizontal thrust may beprovided in response to generating symmetric cyclic control of the firstport rotor, first starboard rotor, second port rotor, and secondstarboard rotor or in response to generating differential thrust of atleast one pair of rotors selected from the group consisting of: i) firstand second port rotors on the one hand and first and second starboardrotors on the other hand, ii) first port rotor and first starboard rotoron the one hand and second port rotor and second starboard rotor on theother hand. In one embodiment, pitch and roll station-keeping control ofthe fuselage may be provided in response to generating symmetric cycliccontrol of the first port rotor, first starboard rotor, second portrotor, and second starboard rotor to provide horizontal thrust andgenerating differential thrust of at least one pair of rotors selectedfrom the group consisting of: i) first and second port rotors on the onehand and first and second starboard rotors on the other hand, ii) firstport rotor and first starboard rotor on the one hand and second portrotor and second starboard rotor on the other hand so that generatingdifferential thrust in combination with the generating symmetric cycliccontrol induces the fuselage to remain stationary and at a pitch or rollangle with respect to horizontal.

A further method of fixed-wing aircraft control includes providing rotorblade pitch control to a first port rotor coupled to a first port wing,the rotor blade pitch control for the first port rotor selected from thegroup consisting of longitudinal cyclic control, lateral cyclic controland collective pitch control to induce pitch, roll and yaw moments,respectively; and providing rotor blade pitch control to a firststarboard rotor coupled to a first starboard wing, the rotor blade pitchcontrol for the first starboard rotor selected from the group consistingof longitudinal cyclic control, lateral cyclic control and collectivepitch control to induce pitch, roll and yaw moments, respectively.Through such a method, the fixed-wing aircraft pitch, yaw and rollmoments may be accomplished without the benefit of control surfaces on awing. In another embodiment, the method may also include providing rotorblade pitch control to a second port rotor coupled to a second portwing, the rotor blade pitch control selected from the group consistingof longitudinal cyclic control, lateral cyclic control and collectivepitch control; and providing rotor blade pitch control to a secondstarboard rotor coupled to a second starboard wing, the cyclic controlselected from the group consisting of longitudinal cyclic control,lateral cyclic control and collective pitch control.

A fixed-wing aircraft is also disclosed that may include a fuselage, afirst port wing and a first starboard wing extending from opposite sidesof the fuselage, the first port wing and first starboard wing lackingin-flight controllable surfaces; a first port rotor coupled to the firstport wing, the first port rotor driven by a first electric motor andhaving a first swash plate; and a first starboard rotor coupled to thefirst starboard wing; the first starboard rotor driven by a secondelectric motor and having a second swash plate. In one embodiment ofthis aircraft, the first and second swash plates may enable first portrotor blade pitch control and first starboard rotor blade pitch control,each independently, and selected from the group consisting oflongitudinal cyclic control, lateral cyclic control and collective pitchcontrol. The aircraft may also include a second port wing and secondstarboard wing extending from opposite sides of the fuselage, a secondport rotor coupled to the second port wing, the second port rotor drivenby a third electric motor and having a third swash plate, and a secondstarboard rotor coupled to the second starboard wing, the secondstarboard rotor driven by a fourth electric motor having a fourth swashplate.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the figures are not necessarily to scale, emphasisinstead being placed upon illustrating the principals of the invention.Like reference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 illustrates one embodiment of a two-rotor fixed wing aircrafttransitioning from vertical takeoff to horizontal flight;

FIGS. 2A, 2B, and 2C are starboard plan, top and perspective views,respectively, of the two-rotor fixed wing aircraft first illustrated inFIG. 1 and further illustrating pitch up, yaw right and rolling flightcontrol inputs, respectively;

FIG. 3A is a table illustrating pitch, roll, yaw and thrust effectorinputs and associated graphical representations of the two-rotor fixedwing aircraft illustrated in FIGS. 1 and 2;

FIG. 3B is a table describing embodiments of effector control for thetwo-rotor fixed-wing aircraft illustrated in FIGS. 1, 2A, 2B, and 2C;

FIG. 3C is another table describing embodiments of effector control forthe two-rotor rixed-wing aircraft illustrated in FIGS. 1, 2A, 2B, and2C;

FIGS. 4A, 4B, and 4C are front plan, top plan and port plan views,respectively, of another embodiment of a fixed-wing aircraft that hasfour rotors and is operable for vertical take-off and landing;

FIG. 5 is a table describing embodiments of a vertical flightorientation mode and associated control effectors for the four-rotorfixed-wing aircraft illustrated in FIGS. 4A, 4B, and 4C;

FIG. 6 is a table describing embodiments of a horizontal flightorientation mode and associated control effectors for the four-rotorfixed-wing aircraft illustrated in FIGS. 4A, 4B, and 4C;

FIGS. 7A, 7B, and 7C illustrate one embodiment of vehicle orientationand control of the four-rotor fixed-wing aircraft during calmconditions, horizontal-vectored wind conditions, and deck rollconditions, respectively;

FIGS. 8A, 8B, 8C are top plan, front plan and perspective views,respectively, of another embodiment of a four-rotor fixed-wing aircraft;

FIG. 9 is one embodiment of a system for use with a four-rotor ortwo-rotor (not illustrated) fixed-wing aircraft operable for shipboardlaunch and on station loiter over land using satellite communications;and

FIG. 10 is a block diagram illustrating one embodiment of the powerplant and energy stores for use with a four-rotor fixed-wing aircrafthaving four electric motors.

DETAILED DESCRIPTION

A vertical take-off and landing (VTOL) air vehicle is disclosed with oneor more wings that can take off and land vertically using a two or morerotors that are operable to lift the air vehicle vertically upwards,transition the air vehicle to horizontal flight, and then transition itback to vertical flight to land the air vehicle vertically downwards.During vertical flight, the wing(s) may be orientated vertically and sonot contribute vertical lift while the vehicle is moving up or down(e.g., the wings are pointed upwards). When airborne, the air vehiclecan translate horizontally while maintaining in its verticalorientation, at least substantially (e.g., sliding from side-to-side),and may transition to forward flight by using its rotors to rotate theair vehicle from an at least generally vertical to an at least generallyhorizontal orientation and then back to an at least generally verticalflight from an at least generally horizontal flight for landing. Inforward flight, the one or more wings generate lift and the rotors aredirected to propel the vehicle generally forward. In this manner, theair vehicle can utilize the efficiency of lift generated by a wing whilein forward flight to maximize endurance, but does not require a lengthyhorizontal runway to take off and land given the capability to take offand land vertically.

In embodiments, attitudinal control for the vehicle comes entirely fromthe means of propulsion without the benefit of aerodynamic controlsurfaces, such as ailerons, an elevator, or rudder. Without controlsurfaces on the structure of the vehicle (which typically are placed atthe trailing edges of the wing or stabilizer), the vehicle is lighter,more efficient (aerodynamic), more reliable, less complex and generallymore rugged. Being more rugged allows the air vehicle to be subjected tophysical conditions and handling that a vehicle with control surfaceswould not typically or otherwise be subject to without damage orpotential adverse effects on its control and operation. For example, anair vehicle without control surfaces on its structure could landvertically into bushes or rocky terrain without potential for laterflight control problems due to damaged flight control surfaces.Likewise, without control surfaces the air vehicle requires lessmaintenance and is less susceptible to being damaged in handling, suchas when being moved about on board a ship. Without control surfaces onthe air vehicle, drag is reduced. In other embodiments, some controlsurfaces may be provided to supplement attitudinal control that isotherwise provided by the means of propulsion.

In embodiments, the means for propulsion is at least two rotorsrotatably attached to a wing through respective electric motors and eachincluding a swash plate that can provide pitch, yaw and roll control ofthe air vehicle by varying blade rotation rate (rpm) and/or blade pitch,such as with either/or cyclic or collective pitch control. In verticalflight (or at least generally vertical) a majority of the lift,attitudinal control, and propulsion may be generated by the at least twopropellers; and in horizontal flight (or at least generally horizontal)the majority of lift may be generated by the wing surfaces, and vehicleattitudinal control and propulsion may be generated by the at least tworotors. That is, for horizontal flight, the air vehicle's pitch, yaw,and roll control would be provided through the differential thrust androtational moments created by the at least two rotors, each rotorconsisting of at least two or three rotatable rotor blades havingcontrollably variable pitch through the use of, for example, a swashplate having two or three axes of control. In embodiments, aerodynamiccontrol surfaces, such as an elevator and ailerons, may be provided tosupplement attitudinal control in vertical and horizontal flight.

FIG. 1 shows an embodiment of a two-rotor fixed wing air vehicle 100that may have a fuselage 110 coupled between port and starboard wings(115, 120), and including port and starboard rotors (125, 130). The portand starboard rotors (125, 130) are coupled to and driven by respectiveport and starboard electronic motors (135, 140) through respective portand starboard swash plates (145, 150) that provide collective controland, preferably, single-axis cyclic pitch control of the rotor blades155. In another embodiment, the swash plates (135, 150) may provide forcollective control and two-axis cyclic pitch control of the rotor blades155. In a further embodiment, the port and starboard wings (115, 120)have port and starboard elevons (160, 165) spanning approximately therotor wash behind the port and starboard rotors (125, 130),respectively, to supplemental pitch and/or roll attitudinal control ofthe aircraft 100. For example, if supplementary pitch control isdesired, such as for use in the transition between vertical flight andhorizontal flight, the elevons (160, 165) would be actuated in a“flap-down” configuration to induce a pitch-forward moment in theaircraft. Similarly, if supplementary roll control is desired, theelevons (160, 165) may be operated as ailerons would be on aconventional wing and vertical/horizontal stabilizers aircraft. Forforward and backwards transitioning of the air vehicle during verticalflight, the elevons (160, 165) may be used to maintain (at leastgenerally) the vertical orientation of the air vehicle by generating amoment counteracting the lift generated by the wing with the airflowover it from the prop wash.

The aircraft is illustrated as disposed initially on the ground on itslanding gear 170 and oriented in a vertical position at landed positionA. Vertical take-off of the aircraft 100 is accomplished as verticalthrust is supplied by the first port rotor 125 and first starboard rotor130, as driven by the first port electric motor and the first starboardmotor, respectively (135, 140). The rotors (125, 130) are operable todevelop symmetric or differential thrust (X1, X2) using angular velocitycontrol or collective control inputs, and symmetric or differentialrotational moments using cyclic control inputs, to collectively enablepitch, roll, yaw and vertical/horizontal acceleration. For purposes ofthis application, the inertial frame of reference is provided in FIG. 2Cand vertical/horizontal directions provided in FIG. 1.

The air vehicle may transition from the landed position (position A) tovertical flight and then to horizontal flight (position B) where amajority of lift is provided by the wings (115, 120). Attitudinalcontrol (pitch, roll, yaw) may be provided during both vertical flightand horizontal flight by the rotors (125, 130) as respective pitches ofthe rotor blades 155 are guided by the swash plates (145, 150) and asthe rotors (125, 130) are rotationally driven by the electric motors(135, 140). Horizontal thrust (Y₁, Y₂) during horizontal flight issufficient to overcome parasitic and induced drag of the wings (115,120) and fuselage 110 during cruise, loitering and further horizontalconfiguration ascent.

FIGS. 2A, 2B, and 2C are starboard plan, top and perspective views,respectively, illustrating pitch up, yaw right and roll flight controlforces, respectively, of the two-rotor aircraft. As shown in the sideview of FIG. 2A, with the air vehicle 100 in forward flight, a greaterthrust T1 may be created below the center of the rotor(s) and thus belowthe center of mass M of the air vehicle 100 than the thrust T2 producedabove the center of the rotor(s) and the center of mass M of the airvehicle 100 using cyclic control of the rotors (125, 130) by means ofswash plates (145, 150). In some embodiments the hub and/or rotor bladescan be hinged or gimbaled so that as the swash plate (145, 150) movesthe rotor will displace at an angle relative to its initial position (orto the air vehicle), associated with the swash plate displacement,resulting in the thrust vector being angled relative to its initialposition (e.g., directly forward), where a component of this angledforce vector will impart a force on the air vehicle to cause it torotate (e.g., pitch). The differential forces created and resultingrotational moments will cause the air vehicle 100 to pitch up, ifnegative rotational moments are created from the cyclic control inputs,or pitch down, if positive rotational moments are created from thecyclic control inputs. Similarly, a right roll of the fuselage 110 maybe induced if the port rotor 125 generates a positive rotational momentin response to actuation of the port swash plate 145 and the starboardrotor 130 generates a negative rotational moment in response toactuation of the starboard swash plate 150.

In FIG. 2B, the air vehicle is illustrated during forward flight in itshorizontal flight orientation, with yaw control affected by differentialthrust (XPORT, XSTARBOARD) of the port and starboard rotors (125, 130).In its horizontal flight orientation, differential thrust (XPORT,XSTARBOARD) of the rotors (125, 130) may be accomplished throughasymmetric collective control provided by the port and starboard swashplates (145, 150) and/or, in a non-preferred embodiment, by differentialmotor angular rate control (rotor RPM) of the port and starboard rotors(125, 130) using control of the port and starboard electric motors (135,140). For example, a right-hand yaw moment (yaw to the starboard side)may be induced by i) increasing thrust generated by the port rotor 125,ii) decreasing thrust generated by the starboard rotor 130, or by iii)both increasing thrust generated by the port rotor 125 and decreasingthrust generated by the starboard rotor 130. Increased thrust generatedby a particular rotor may be accomplished by increasing pitch angles ofassociated rotor blades 155 through collective actuation or, in anon-preferred embodiment, by increasing angular rotation (RPM) of theparticular rotor as driven by the associated electric motor. Similarly,decreased thrust generated by a particular rotor may be accomplished bydecreasing pitch angles of associated rotor blades 155 throughcollective actuation or by decreasing angular rotation (RPM) of theparticular rotor as driven by the associated electric motor.

In an alternative embodiment, symmetric cyclic control may be providedby the port rotor 125 and starboard rotor 130 to produce asymmetric leftand right positioned blade thrusts (illustrated with dashed lines) toproduce a net yaw right of moment. More particularly, port swash plate145 actuates asymmetric blade pitch in the port rotor 125 such thatblades passing left (region 155 a) of the port rotor 125 generategreater thrust than blades passing right (region 155 b) of the portrotor 125. Similarly, blades passing left (region 155 a) of thestarboard rotor 130 generate greater thrust than blades passing right(region 155 b) of the starboard rotor 130, with all blades collectivelygenerating a net yaw right of the fuselage 110 through the port andstarboard wings (115, 120).

FIG. 2C is a perspective view illustrating cyclic control of the rotorsproducing left roll of the fuselage. In one embodiment, the left roll ofthe fuselage is induced in response to generating in the first portrotor 125 a negative rotational moment M_(PORT) in response to actuationof the first port swash plate 145 and generating in the first starboardrotor 130 a positive rotational moment M_(STARBOARD) in response toactuation of the first starboard swash plate 150. Similarly, to affect aright roll on the fuselage, a positive rotational moment may begenerated in the first port rotor in response to actuation of the firstport wash plate and a negative rotational moment in the starboard rotorin response to actuation of the first starboard swash plate. The uppitch on the right wing and the down pitch on the left wing causes theair vehicle 100 to roll to the left (as viewed from behind). Similarly,reversing these pitch forces may induce the air vehicle 100 to roll tothe right. Also illustrated in FIG. 2C are horizontal thrust componentsT3, T4, T5, and T6 and indicate thrust magnitudes of associated blades155 at the illustrated rotor blade positions, along with associatedvertical thrust vector components Z₁ (starboard wing), Z₂ (port wing).

FIG. 3A describes embodiments of pitch, roll, yaw and thrust effectorinputs along with associated force vectors and graphical representationsof the two-rotor fixed wing aircraft illustrated in FIGS. 1 and 2. Inrow 1 of FIG. 3A, a front plan view of the aircraft 100 is provided toillustrate one embodiment of nose up positive pitch control of thefuselage 110 through the port and starboard wings (115, 120). Pitch upmay be induced using symmetric pitch cyclic control, such as bygenerating in the port and starboard rotors (125, 130) respectivepositive (and equal) rotational moments in response to actuation of portand starboard swash plates, respectively, that results in a pitch upforce as indicated with two vertical force lines. Left plan and rightplan views of the air vehicle 100 are also provided illustrating a netnose up force vector generated from the nose up symmetric pitch cycliccontrol.

In row 2 of FIG. 3A, a front plan view of the aircraft 100 is providedto illustrate a right (positive) roll of the fuselage. The right(positive) roll may be induced using asymmetric cyclic control of theport and starboard rotors (125, 130), such as by generating in the portrotor 125 a positive rotational moment in response to suitable actuationof the port swash plate and generating in the starboard rotor a negativerotational moment in response to suitable actuation of the starboardswash plate. Although not illustrated in FIG. 3A, a left roll of thefuselage may also be provided using asymmetric cyclic control of portand starboard rotors (125, 130). For example, a negative rotationalmoment may be generated in the port rotor in response to suitableactuation of the port swash plate, and a positive rotational momentgenerated in the starboard rotor in response to suitable actuation ofthe starboard swash plate, resulting in the left roll of the fuselage110. Asymmetric control of elevons may also supplement left roll of thefuselage (see FIG. 2B), such as by extending the port elevon 160 up toreduce lift on the port wing 115 and extending the starboard elevon 165down to increase lift on the starboard wing 165.

In row 3 of FIG. 3A, a top plan view of the aircraft 100 is provided toillustrate right (positive) yaw of the fuselage. The yaw may be inducedusing differential thrust of the port and starboard rotors (125, 130).Such differential thrust may be provided by either asymmetric collectivecontrol or differential rotational speed control of the port andstarboard rotors (125, 130). As illustrated in line 3 of FIG. 3A, noseright yaw (positive) may be induced about the fuselage by the port rotor125 providing more thrust than the starboard rotor 130. Similarly, noseleft yaw (negative) may be induced about the fuselage by the port rotor125 providing less thrust than the collective rotor 130. In oneembodiment, differential thrust is provided using differential rates ofrotation of the port and starboard rotors (125, 130), such as would beprovided by port and starboard electric motors (135, 140) driving theport and starboard rotors (125, 130) at different revolutions-per-minute(RPMs). In another embodiment described in FIG. 3A, asymmetriccollective control of the rotors (125, 130) are used to providedifferential thrust, such as by providing greater relative collectivecontrol of the port rotor 125 and less relative collective control ofthe starboard rotor 130.

In row 4 of FIG. 3A, a top plan view of the aircraft 100 is alsoprovided to illustrate one embodiment of application of thrust. In oneembodiment, thrust adjustments may be made using symmetric collective(forward positive) control of the rotors (125, 130). The rotors (125,130) may be driven at a constant angular rotation rate by port andstarboard electric motors (135, 140), with rotor thrust varied bycollective blade pitch adjustments made by respective port and starboardswash plates (145, 150). In order to increase forward thrust, the portand starboard swash plates (145, 150) may increase respective collectivecontrol inputs to increase the pitch of each blade 155 in a symmetricmanner. In order to decrease forward thrust, the port and starboardswash plates (145, 150) may decrease respective collective controlinputs to decrease the pitch of each blade 155 in a symmetric manner.

FIGS. 3B and 3C are tables describing different flight control effectorembodiments available to accomplish pitch in horizontal or verticalflight, roll, yaw, and coordinated turns for the two-rotor fixed-wingaircraft illustrated in FIGS. 1, 2A, 2B, and 2C, along with associatedgraphics illustrating associated forces. Pitch and pitch to/fromvertical flight control may be accomplished by means of at least twoeffector embodiments. In Embodiment 1 (line 1), symmetric cyclic controlinputs may be provided as between the port and starboard rotors (125,130). For example, pitch-up control of the fuselage 110 may be inducedin response to generating a positive rotational moment in each of theport and starboard rotors (125, 130) (i.e., symmetric cyclic rotorcontrol) in response to suitable symmetric actuation of respective portand starboard swash plates (145, 150). Similarly, pitch down control ofthe fuselage 110 may be induced in response to generating a negativerotational moment in each of the port and starboard rotors (125, 130) inresponse to suitable symmetric actuation of respective port andstarboard swash plates (145, 150). In Embodiment 2 of pitch and pitchto/from vertical flight control illustrated in FIG. 3C, such pitcheffector control may be supplemented using symmetric actuation of portand starboard elevons (160, 165). For example, if port and starboardrotors (125, 130) are inducing pitch up of the fuselage 110, the portand starboard elevons may be actuated symmetrically (i.e., substantiallysimilar effector control inputs) to provide additional fuselage pitch-upforce.

Roll control may be accomplished in at least two different effectorcontrol embodiments. In Embodiment 1 illustrated in FIG. 3B (line 2),asymmetric cyclic control of the port and starboard rotors (125, 130)may induce a roll of the fuselage. For example, a left roll of thefuselage 110 may be induced by generating negative and positiverotational moments in port and starboard rotors (125, 130),respectively, in response to actuation of port and starboard swashplates (145, 150), respectively. Similarly, a right roll of the fuselagemay be induced by generating positive and negative rotational moments inport and starboard rotors (125, 130) respectively, in response toactuation of the port and starboard swash plates (145, 150),respectively. In Embodiment 2 of the aircraft's roll effector controlillustrated in FIG. 3C, the asymmetric cyclic control of the port andstarboard rotors (125, 130) may be supplemented by complementaryasymmetric actuation of the port and starboard elevons (160, 165). Forexample, if port and starboard rotors (125, 130) are inducing a leftroll, then the port and starboard elevons (160, 165) may be actuatedasymmetrically to provide additional fuselage left roll force, similarin operation to aileron control in aircraft having more typical aileronand fin/elevator control surfaces.

Yaw control may be accomplished with at least three different effectorcontrol embodiments. In Embodiment 1 described in FIG. 3B (line 3), ayaw moment may be induced about the fuselage 110 in response togenerating asymmetric collective control (alternatively referred to as“asymmetric collective” control) between the port and starboard rotors(125, 130). For example, a right (positive) yaw may be induced byincreasing relative collective control of the port rotor 125 and/ordecreasing relative collective control of the starboard rotor 130assuming straight and steady-state initial flight attitude. Similarly, aleft (negative) yaw may be induced about the fuselage 110 by decreasingrelative collective control of the port rotor 125 and/or increasingrelative collective control of the starboard rotor 130.

In Embodiment 2 (line 3) illustrate in FIG. 3C, yaw control may beaccomplished using differential motor RPM control of the port andstarboard electric motors (135, 140) driving respective port andstarboard rotors (125, 130). For example, a right (positive) yaw may beinduced about the fuselage 110 by increasing the RPM of port rotor 125,by means of a proportional increase in the RPM of the port electricmotor 135, and/or decreasing the RPM of the starboard rotor 130 by meansof a proportional decrease in the RPM of the starboard electric motor140. Similarly, a left (negative) yaw may be induced about the fuselage110 by and decreasing the RPM of the port rotor 125 by means of aproportional decrease in the RPM of the port electric motor 135, and/orincreasing the RPM of the starboard rotor 130 by means of a proportionalincrease in the RPM of the starboard electric motor 140.

In Embodiment 3 (line 3) illustrated in FIG. 3C, yaw control may beaccomplished using asymmetric collective control of the port andstarboard rotors (125, 130) with differential motor RPM control of theport and starboard electric motors (135, 140). For example, a right(positive) yaw may be induced in the fuselage 110 by increasingcollective control of the port rotor 125 and/or decreasing relativecollective control of the starboard rotor 130 in association withincreased motor RPM control of the port electric motor 135 and/ordecreased motor RPM control of the starboard electric motor 140.Similarly, a left (negative) yaw may be induced in the fuselage 110 bydecreasing collective control of the port rotor on 25 and/or increasingrelative collective control of the starboard rotor 130 in associationwith decreased motor RPM control of the port electric motor 135 and/orincreased motor RPM control of the starboard electric motor 140.

FIGS. 3B and 3C also describes at least four different effector controlembodiments that may be used to accomplish coordinated turns using theinventive system described herein. In Embodiment 1 described in FIG. 3B(line 4), a coordinated turn of the port and starboard wings may beaccomplished by using asymmetric cyclic control of port and starboardrotors (125, 130) approximately concurrently with asymmetric collectivecontrol of the port and starboard rotors (125, 130). For example, toaccomplish a coordinated right turn, asymmetric cyclic control of portand starboard rotors (125, 130) may be accomplished by generating in theport rotor 125 a positive rotational moment and generating in thestarboard rotor 130 a negative rotational moment, each approximatelyconcurrently with increasing collective control of the port rotor 125and/or decreasing collective control of the starboard rotor 130. Inanother example, to accomplish a coordinated left turn, asymmetriccyclic control of port and starboard rotors (125, 130) may beaccomplished by generating in the port rotor 125 a negative rotationalmoment and generating in the starboard rotor 130 a positive rotationalmoment, each approximately concurrently with decreasing collectivecontrol of the port rotor 125 and/or increasing collective control ofthe starboard rotor 130.

In Embodiment 2 (line 4) illustrated in FIG. 3C, the coordinated turnmay be accomplished by using asymmetric port and starboard elevons (160,165) and approximately concurrent asymmetric collective control of portand starboard rotors (125, 130). For example, to accomplish acoordinated right turn, port elevon 160 may be actuated to induceincreased lift in the port wing 115 and starboard elevon 165 actuated toinduce decreased lift in the starboard wing 120 each approximatelyconcurrently with increased collective control of the port rotor 125and/or decreased relative collective control of the starboard rotor 130.Similarly, to accomplish a coordinated left turn, port elevon 160 may beactuated to induce decreased lift in the port wing 115 and starboardelevon 165 actuated to induce increased left in the starboard wing 120,each approximately concurrently with decreased collective control of theport rotor 125 and/or increased relative collective control of thestarboard rotor 130.

In Embodiment 3 (line 4) illustrated in FIG. 3C, the coordinated turnmay be accomplished by using i) asymmetric cyclic control of the portand starboard rotors (125, 130) with approximately concurrent ii)asymmetric collective control of the port and starboard rotors (125,130) and iii) asymmetric control of port and starboard elevons (160,165). For example, a coordinated right turn may be accomplished inaccordance with the right turn described above for Embodiment 2, andwith the additional asymmetric cyclic control of port and starboardrotors (125, 130) such as by generating in the port and starboard rotors(125, 130) positive and negative rotational moments, respectively, inresponse to actuation of the port and starboard swash plates (145, 150),respectively. Similarly, a coordinated left turn may be accomplished inaccordance with the left turn described above for and Embodiment 2, andwith the additional asymmetric cyclic control of port and starboardrotors (125, 130) such as by generating in the port and starboard rotors(125, 130) negative and positive rotational moments, respectively inresponse to actuation of the port and starboard swash plates (145, 150),respectively.

In Embodiment 4 (line 4) of FIG. 3C, the coordinated control may beaccomplished by using i) asymmetric cyclic control of the port andstarboard rotors (125, 130) with approximately concurrent ii) asymmetricactuation of the port and starboard elevons (160, 165); and with iii)differential motor RPM control of the port and starboard electric motors(135, 140).

FIGS. 3B and 3C also describe at least three different effector controlembodiments that may be used to accomplish a slow horizontal translationusing the inventive system described herein. In Embodiment 1 (line 5),the slow horizontal translation may be accomplished by using symmetriccyclic (non-zero) rotor control of port and starboard rotors. InEmbodiment 2 (line 5) illustrated in FIG. 3C, the slow horizontaltranslation may be accomplished using i) symmetric cyclicle (non-zero)rotor control of all rotors, and ii) elevon control maintain a morevertical orientation of the aircraft. In Embodiment 3 (line 5)illustrated in FIG. 3C, horizontal translation may be accomplished usingasymmetric collective control of the port rotor vs. the starboard rotor.

Although FIGS. 3A and 3B are described primarily in relation to atwo-rotor fixed-wing aircraft 100, in a non-preferred embodiment sucheffector control inputs may be utilized to also provide attitudinal andthrust control of a four-rotor fixed-wing aircraft having two wings anda horizontal stabilizer/elevator configuration, such as that illustratedin FIGS. 4A, 4B, and 4C. In such an application, effector controls wouldpreferably reside on one of the two main wings of the four-rotorfixed-wing aircraft.

FIGS. 4A, 4B, and 4C are front plan, top plan and port plan views,respectively, of another embodiment of a fixed-wing aircraft that hasfour rotors and is operable for vertical takeoff and landing. An aftmain wing 401 has aft port and aft starboard wings (402, 404) joined ata fuselage 406. A forward main wing 408 has forward port and forwardstarboard wings (410, 412) also joined at the fuselage 406. An aft portswash plate 414 is coupled between an aft port rotor 416 and an aft portelectric motor 418, the aft port electric motor 418 coupled to the aftport wing 402. An aft starboard swash plate 420 is coupled between anaft starboard rotor 422 and an aft starboard electric motor 424, the aftstarboard electric motor 420 coupled to the aft starboard wing 404. Aforward port swash plate 426 may be coupled between a forward port rotor428 and forward port electric motor 430, the forward port electric motor430 coupled to the forward port wing 410. A forward starboard swashplate 432 may be coupled between a forward starboard rotor 434 andforward starboard electric motor 436, the forward starboard electricmotor 436 coupled to the forward starboard wing 412. In one embodiment,a horizontal stabilizer 438 may be coupled to the fuselage 406, and anelevator 440 may be rotatably coupled to horizontal stabilizer 438, withthe fuselage 406 coupled between the forward port wing 410 and forwardstarboard wing 412. A port aileron 442 may be rotatably disposed on atrailing edge 444 of the aft port wing 402; and a starboard aileron 446may be rotatably disposed on a trailing edge 448 of the aft starboardwing 404. Aft and forward landing gear (450, 452) may be attached to theaft port wing 402 and aft starboard wing 404, respectively. A thirdlanding gear 454 may be attached to the horizontal stabilizer 438, suchas on opposite longitudinal sides of the horizontal stabilizer 438.

For purposes of the previous discussion and following tabledescriptions, the described pitch, yaw, and roll movements resultingfrom “symmetric” and “differential” cyclic rotor control, collectiverotor control and motor RPM, assume symmetric or near symmetric rotorplacement about the center of mass of the air vehicle, assume identicalor near identical electric motor outputs and assume symmetric or nearsymmetric parasitic drag of the aircraft's structure about its center ofmass in horizontal and vertical flight modes. In real-worldapplications, bias or trim effector inputs may be provided to compensatefor weight-balance deviation and for non-symmetrical parasitic drag ofthe aircraft's structure, to maintain the effectiveness of the followingeffector controls:

Symmetric Collective effector control—Application of the same or similarcollective control inputs as between two sets of rotors by respectiveswash plates (where a set may be a single rotor) that results in thesame or similar rotor force vectors as between such sets.

Asymmetric Collective effector control—Application of dissimilarcollective control inputs as between two sets of rotors by respectiveswash plates (where a set may be a single rotor) that results indissimilar rotor force magnitude and but in the same or similar vectorforce direction as between such sets.

Asymmetric Cyclic effector control—Application of dissimilar cycliccontrol inputs as between two sets of rotors by respective swash plates(where a set may be a single rotor) that results in dissimilar rotorrotational moment magnitude and in the opposite rotational momentdirection as between such sets.

Symmetric Cyclic effector control—Application of the same or similarcyclic control inputs as between two sets of rotors by respective swashplates (where a set may be a single rotor) that results in the same orsimilar rotor rotational moment magnitude and direction as between suchsets. Symmetric Cyclic effector control may also be used to refer to allrotors having the same rotational moment magnitude and in the same orsimilar rotational moment direction.

Differential Motor RPM—Application of dissimilar rotational velocitiesas between two sets of motors (where a set may be a single motor), wheresuch sets of motors are configured to translate such dissimilarrotational velocities into proportionally dissimilar rotor forcemagnitudes as between sets but in the same or similar vector forcedirection.

FIG. 5 describes three flight control configuration embodiments that mayeach be used to affect pitch, yaw, and roll control of the four-rotorfixed-wing aircraft first illustrated in FIGS. 4A, 4B, and 4C during thevehicle's vertical flight orientation, such as during takeoff and hover.Pitch to horizontal flight from vertical orientation may be accomplishedby means of at least two effector embodiments. In flight controlconfiguration Embodiment 1 (line 1), pitch control of the fuselage 406may be provided in response to providing differential motor RPM controlbetween the aft port rotor 416 and/or the aft starboard rotors 422 onthe one hand, and the forward port rotor 428 and/or the forwardstarboard rotor 434 on the other. In Embodiment 2 (line 1), pitchcontrol of the fuselage may be provided in response to providingasymmetric collective control between the aft port rotor 416 and aftstarboard rotor 422 on the one hand, and the forward port rotor 428 andforward starboard rotor 434 on the other.

FIG. 5 also describes two different effector control embodiments thatmay be used to accomplish slow horizontal translation when the airvehicle 400 is in a vertical orientation mode. In Embodiment 1 (line 2),slow horizontal translation of the aft and forward port wings (402, 410)and aft and forward starboard wings (404, 412) is induced by providingsymmetric cyclic control of all rotors (416, 428, 422, and 434). InEmbodiment 2 (line 2), slow horizontal translation in the verticalorientation mode may be provided by generating different collectivebetween the aft port and starboard rotors (416, 422) on the one hand,and forward port and starboard rotors (428, 434) on the other hand. Inan alternative embodiment, the horizontal translation may be provided bygenerating different collective between the aft and forward port rotors(416, 428) on the one hand and aft and forward starboard rotors (422,434) on the other hand.

A static non-zero roll station-keeping control of the fuselage may beaccomplished during a hover/vertical orientation mode by means of atleast two effector embodiments. In Embodiment 1 (line 3), asymmetriccollective control may be generated between aft and forward starboardrotors (422, 434) on the one hand and aft and forward port rotors (416,428) on the other, each approximately concurrently with symmetric cycliccontrol of the rotors (422, 434, 416, 428). In Embodiment 2 (line 3)differential motor RPM control may be provided between aft and forwardstarboard rotors (422, 412) on the one hand, and aft and forward portrotors (416, 428) on the other, each approximately concurrently withnon-zero symmetric cyclic control of all rotors (422, 434, 416, 428).

A static non-zero pitch angle station-keeping control of the fuselagemay also be accomplished during the hover/vertical orientation mode bymeans of at least two effector embodiments. In Embodiment 1 (line 4)illustrated in FIG. 5, asymmetric collective control may be generatedbetween the aft port and aft starboard rotors (416, 422) on the one handand forward port and forward starboard rotors (416, 434) on the other,approximately concurrently with symmetric cyclic control of aft andforward port rotors (416, 428) on the one hand and aft and forwardstarboard rotors (422, 434) on the other. In Embodiment 2 (line 4), thepitch angle station-keeping may be provided by generating differentialmotor RPM control between the aft port rotor 416 and aft starboard rotor422 on the one hand, and the forward port rotor 428 and forwardstarboard rotor 434 on the other, approximately concurrently withsymmetric cyclic control of the aft port rotor 416, forward port rotor428, aft starboard rotor 422 and forward starboard rotor 434.

A yaw moment may be induced about the fuselage during the hover/verticalorientation mode by means of at least two effector embodiments. InEmbodiment 1 (line 5) of FIG. 5, the yaw moment may be induced inresponse to asymmetric cyclic control of the aft and forward port rotors(416, 428) on the one hand and aft and forward starboard rotors (422,434) on the other hand. In Embodiment 2 (line 5), the yaw moment may beinduced in response to differential motor RPM control of the aft portrotor 416 and forward starboard rotor 434 on the one hand, and forwardport rotor 428 and aft starboard rotor 422 on the other.

Vertical takeoff may be provided by means of at least two effectorembodiments. In Embodiment 1 (line 6), the takeoff may be induced inresponse to symmetric motor RPM control of all rotors (422, 434, 416,428). In Embodiment 2 (line 6) of FIG. 5, takeoff may be induced in thefuselage in response to symmetric collective control of all rotors (422,434, 416, 428).

Although FIG. 5 describes two aircraft configuration embodiments foraffecting various aircraft attitudinal and translation controls, theeffector controls in one aircraft configuration embodiment may be usedin another embodiment. For example, in any particular aircraftconfiguration embodiment, slow horizontal translation may beaccomplished with either symmetric cyclic (non-zero) rotor control orasymmetric collective rotor control, as described in FIG. 5, line 2.

FIG. 6 describes three flight control embodiments that may be usedcollectively to affect pitch, yaw, and roll control of the four-rotorfixed-wing aircraft first illustrated in FIGS. 4A, 4B, and 4C during thevehicle's horizontal flight orientation, such as when the aft andforward main wings (401, 408) are providing all or substantially all ofthe vertical lift during cruise or loiter. Pitch control of the fuselageto transition from horizontal flight orientation to vertical flightorientation, such as in preparation for landing or hover, may be inducedabout the fuselage during flight in its horizontal flight orientation byleast three different aircraft control configuration embodimentsdescribed in FIG. 6. In flight control Embodiment 1, pitch to verticalflight may be induced by providing asymmetric collective control betweenaft port and aft starboard rotors (416, 422) on the one hand, andforward port and forward starboard rotors (428, 434) on the other, andby providing approximately current and complementary elevator actuation.In flight control Embodiment 2 (line 1), pitch control of the aircraftis accomplished in response to providing asymmetric collective controlbetween aft port and aft starboard rotors (416, 422) on the one hand,and forward port and forward starboard rotors (428, 434) on the other,without the use of elevator actuation. In flight control Embodiment 3(line 1), pitch control for the fuselage may be induced by providingdifferential motor RPM control between the aft port and aft starboardmotors (418, 424) on the one hand and the forward port and forwardstarboard rotors (428, 434) on the other.

Pitch control of the fuselage may be provided during flight while in theaircraft's horizontal orientation using least three different aircraftcontrol configuration embodiments described in FIG. 6. In flight controlEmbodiment 1 (line 2), pitch may be induced by providing elevatorcontrol without the use of asymmetric collective rotor control. InEmbodiment 2 (line 2), pitch control may be induced by providingasymmetric collective control between aft port and aft starboard rotors(416, 422) on the one hand, and forward port and forward starboardrotors (428, 434) on the other, preferably without the use of elevatoractuation. In Embodiment 3 (line 2), pitch control for the fuselage maybe induced by providing differential motor RPM control between the aftport and aft starboard motors (418, 424) on the one hand and the forwardport and forward starboard rotors (428, 434) on the other, preferablywithout the benefit of elevator actuation or asymmetric collective rotorcontrol.

A roll moment may be induced about the fuselage during flight in itshorizontal flight orientation by least three different aircraft controlconfiguration embodiments described in FIG. 6. In flight controlEmbodiment 1 (line 3), a roll may be induced by providing actuation ofthe port and starboard ailerons (442, 446) rotatably coupled to the aftport wing 402 and aft starboard wing 404, respectively. In analternative embodiment, port and starboard ailerons may also be providedon the forward port and starboard wings (410, 412) or on both forwardand main wings (401, 408). In Embodiment 2 (line 3), roll control may beinduced by providing asymmetric cyclic rotor control of the aft andforward port rotors (416, 428) on the one hand, and the aft and forwardstarboard rotors (422, 434) on the other. In Embodiment 3 (line 3), rollcontrol may be provided by differential motor RPM control of the forwardand aft port motors (430, 418) on the one hand, and forward and aftstarboard motors (436, 424) on the other hand.

A yaw moment may be induced about the fuselage during flight in itshorizontal flight orientation by least three different aircraft controlconfiguration embodiments described in FIG. 6. In flight controlEmbodiments 1 and 2 (line 4), a yaw moment may be induced about thefuselage in response to asymmetric collective control between the aftand forward port rotors (416, 428) on the one hand, and the aft andforward starboard rotors (422, 434) on the other hand. In Embodiment 3(line 4), the yaw moments may be induced in response to differentialmotor RPM control between the aft and forward port rotors (416, 428) onthe one hand, and the aft and forward starboard rotors (422, 434) on theother.

A coordinated turn of the forward and aft main wings may also beaccomplished during flight in its horizontal flight orientation by leastthree different aircraft control configuration embodiments described inFIG. 6. In flight control Embodiment 1 (line 5), a coordinated turn ofthe aircraft 400 may be accomplished by providing asymmetric aileroncontrol between the port aileron 424 and the starboard aileron 446,concurrently with asymmetric collective rotor control between aft andforward port rotors (416, 428) on the one hand and aft and forwardstarboard rotors (422, 434) on the other. In aircraft configurationEmbodiment 2 (line 5), coordinated turn of the aircraft 400 may beaccomplished by providing asymmetric cyclic control between the aft andforward port rotors (416, 428) on the one hand, and aft and forwardstarboard rotors (422, 434) on the other, approximately concurrentlywith providing asymmetric collective control between aft and forwardport rotors (416, 428) on the one hand and aft and forward starboardrotors (422, 434) on the other.

FIGS. 7A, 7B, and 7C illustrate the affect of several of the effectorcontrol modes described in FIG. 5 for use in different weatherconditions that may be encountered when attempting to land on a movingship deck surface. More particularly, FIG. 7A illustrates aircraft 400in a vertical orientation while hovering over a ship deck 700 in calmwind conditions. The aft and forward port rotors (416, 428) and aft andforward starboard rotors (422, 434) may maintain the aircraft 400 in astatic hover position and in level flight (i.e, pitch and roll angles at0° with respect to a horizontal plane) such as by the use of symmetriccollective control and/or motor RPM control of each rotor (416, 422,428, 434) and symmetric cyclic control of each rotor (416, 422, 428,434) at 0° relative to a vertical axis. In FIG. 7B, wind is illustratedoff of the aircraft's 400 port wings (402, 410), necessitating activeflight control such as that described in Embodiments 1 and 2 in line 2of FIG. 5, which describe slow horizontal translation control of thefuselage while in the hover/vertical orientation. In an alternativeembodiment, such as when the wind is coming horizontally from theforward position/orientation, Embodiments 1 and 2 in line 2 of FIG. 5may also be used to counteract wind forces impinging on the aircraft tomaintain a static lateral position above the ship deck by adjustingsymmetric cyclic to provide a thrust in the forward (x-axis) direction.In FIG. 7C, no wind is illustrated, but the ship deck is illustrated atan instantaneous pitch and roll angle from level suggesting the use ofdynamic pitch and roll effector control of the aircraft 400 toaccomplish a landing using, for example, a combination of control inputsselected from embodiments described in lines 3 and 4 of FIG. 5. Forexample, active pitch and roll angle management may be induced in thefuselage 446 as the aircraft 400 descends, to reduce undesirable lateraltranslation during descent, but allowing for proper orientation of thelanding gear (450, 452 and 454) upon contact with the ship deck 700 evenif the ship deck is rolling.

FIGS. 8A, 8B, 8C illustate another embodiment of a four-rotor fixed-wingaircraft that has a turbine and internal combustion engine (“ICE”) tocharge batteries that provide power to electric motors that drive therotors. The aircraft 800 may have the internal combustion engine 805 andturbine 810 disposed within the fuselage 815. The internal combustionengine may be, for example, a diesel or jet-fueled engine, with one ormore fuel tanks 820 available for the turbine and ice (810, 805)providing for diesel and jet fuel storage. The ICE and turbine may driveone or more generators that are electrically coupled to batteries 825. Apayload 830 having, for example, sensors, and avionics 835 for remotecommunication and control of the aircraft may also be disposed in thefuselage 815. Each rotor 840 may be driven by a respective electricmotor 845 as guided by a respective swash plate 850, with each electricmotor 845 obtaining power either directly from the batteries 825, theelectrical power generated by the ICE 805 or turbine 810 or through somecombination of batteries, ICE, or turbine (825, 805, 810). For example,during cruise or loiter, each electric motor 845 may obtain power fromthe ICE 805. During vertical takeoff, each electric motor 845 may obtainpower from both the ICE 805 and turbine 810, or from the ICE, turbineand batteries, collectively (805, 810, 825).

The aircraft 800 may be provided with four wings 860 in an X-wingconfiguration with the fuselage 815 in the center. The rotors may bearranged symmetrically about the fuselage 815, one rotor on each wing860, and preferably spaced equidistant from the fuselage 815 along arespective wing 860. In one embodiment, each rotor 840 is disposed at arespective wingtip 865 for enhanced attitudinal control of the fuselage815. Although two blades 870 are provided for each rotor 840, each rotormay be a three or four-bladed rotor 840. Four landing gear 875 mayextend from engine nacelles or other supports 880 to enable verticaltake off and landing of the aircraft 800. The landing gear 875 may alsoextend from the fuselage 815, from two or more wings 860 or from somecombination of the fuselage 815, wings 860 or supports 880.

FIG. 9 illustrates one embodiment of a system for use with a fixed-wingaircraft having cyclic and collective control of multiple rotors thatare configured for vertical takeoff and landing via a shipboard launch,and on-station loiter over land using satellite communications. Aircraft900 may takeoff vertically from a vertical flight orientation from aship deck 905 using thrust controlled by means of motor RPM control orcollective rotor control, or both, with takeoff electric power providedto electric motors using a combination of the internal combustion enginegenerator, turbine generator, and previous-stored battery power forsupplemental electric power. The aircraft 900 may pitch forward toestablish a horizontal flight orientation 910 using a flight controlconfiguration embodiment that may include i) differential motor RPMcontrol, ii) or asymmetric collective control (see FIG. 5, line 1).

As a horizontal flight orientation is established, the aircraft mayenter a fuel-efficient horizontal orientation cruise mode 915 (versesvertical orientation cruise), preferably utilizing electrical power fromone of only the internal combustion engine generator (see FIGS. 8A, 8B,8C) to drive the rotors, with primary lift being provided by theaircraft's wings for flight to a loiter station 910. In an alternativeembodiment, either the turbine generator or battery or both may be usedfor cruise power should the internal combustion engine generator beinsufficient or unavailable or if additional electrical power isdesired. In aircraft control embodiments, pitch control about thefuselage may be accomplished using i) elevator actuation, ii) asymmetriccollective control, or iii) differential motor RPM control as describedin line 2 of FIG. 6. Roll control about the fuselage may be accomplishedusing a) ailerons, b) asymmetric cyclic rotor control, or c)differential motor RPM control as described in line 3 of FIG. 6. Yawcontrol about the fuselage may be accomplished using asymmetriccollective control or differential motor RPM control as described inline 4 of FIG. 6. Coordinated turns may be facilitated during horizontalorientation cruise for using x) ailerons and asymmetric collective rotorcontrol, y) asymmetric cyclic rotor control and asymmetric collectiverotor control, or z) differential motor RPM control.

Communication with a command and control station, such as a ship 920,may be facilitated via a satellite 925.

Upon the conclusion of the on-station loiter 910, the aircraft mayreturn 930 to a landing destination such as, for example, the ship deck905. Upon reaching the landing destination, the aircraft may pitch tothe horizontal flight orientation 935 using, for example, differentialmotor RPM control or asymmetric collective control to make the flightorientation change, as effector embodiments are described in FIG. 5,line 1. Slow horizontal translation of the aircraft may be used forfinal landing position control using symmetric cyclic (non-zero) rotorcontrol or asymmetric collective rotor control as described in FIG. 5,line 2. If the landing destination is not level, or if the ship deck isheaving, the aircraft may match the pitch and roll angle of the shipdeck 905 as the aircraft descends using the effector control embodimentsdescribed in FIG. 5, lines 3 and 4.

In an alternative embodiment, the aircraft 900 is a two-rotor aircraftas illustrated in FIGS. 1 and 2A, 2B, 2C and with effectors asconfigured in FIGS. 3A and 3B. As in FIG. 9, the fixed-wing aircraftwould be may takeoff vertically from a vertical flight orientation froma ship deck 905 using thrust controlled by means of motor RPM control orcollective rotor control, or both. The aircraft may pitch forward toestablish a horizontal flight orientation 910 using a flight controlconfiguration embodiment that may include i) symmetric cyclic control,ii) or symmetric cyclic control with symmetric elevons actuation (seeFIG. 3B, line 1). As a horizontal flight orientation is established, theaircraft may enter a fuel-efficient horizontal orientation cruise mode915 (verses vertical orientation cruise), with vertical lift createdprimarily from its wings (115, 120)(see FIG. 1) for flight to a loiterstation 910. In aircraft control embodiments, pitch control about thefuselage may be accomplished using i) symmetric cyclic control or ii)symmetric rotor control and symmetric elevons actuation. Roll controlabout the fuselage may be accomplished using a) asymmetric cyclic rotorcontrol, or b) asymmetric cyclic control. Yaw control about the fuselagemay be accomplished using x) asymmetric cyclic rotor control or y)asymmetric cyclic rotor control and asymmetric elevon actuation. Acoordinated turn may be facilitated using I) asymmetric cyclic rotorcontrol with asymmetric collective rotor control, II) asymmetric elevonactuation with asymmetric collective rotor control, or III) asymmetriccyclic rotor control with asymmetric collective and asymmetric elevonsactuation, or IV) asymmetric cyclic rotor control with asymmetricelevons actuation and differential RPM control.

Upon the conclusion of the on-station loiter 910 by the 2-rotoraircraft, it may return 930 to a landing destination such as, forexample, the ship deck 905. Upon reaching the landing destination, theaircraft may pitch to the horizontal flight orientation using, forexample, either symmetric cyclic rotor control or symmetric cyclic rotorcontrol with symmetric elevons actuation.

FIG. 10 is a block diagram illustrating one embodiment of a hybrid powersystem having power plant and energy stores for use with a four-rotorfixed-wing aircraft having four electric motors. The aircraft 1000 isillustrated having four electric motors 1005 that are in electricalcommunication with the hybrid power system 1010 that may consist of ahover battery 1015, an internal combustion engine generator 1020 and aturbine electric generator 1025. Diesel and jet fuel tanks (1035, 1040)may be in liquid communication with the internal combustion enginegenerator and turbine electric generator, respectively (1020, 1025). Apayload 1045, such as image or thermal sensors, transceivers oratmospheric sensors, may be in electrical communication with the hybridpower system 1005.

While various embodiments of the application have been described, itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof this invention.

What is claimed is:
 1. A fixed-wing aircraft, comprising: a fuselage; a first port wing and a first starboard wing extending from opposite sides of the fuselage, the first port wing and first starboard wing lacking in-flight controllable surfaces; a first port rotor coupled to the first port wing, the first port rotor driven by a first electric motor and having a first swash plate; and a first starboard rotor coupled to the first starboard wing, the first starboard rotor driven by a second electric motor and having a second swash plate; wherein the first and second swash plates enable first port rotor blade pitch control and first starboard rotor blade pitch control each independently selected from the group consisting of longitudinal cyclic control, lateral cyclic control and collective pitch control. 